Dear Colleagues - We are proud to announce the publication of:
*Elwen, S.H*., R.H. Leeney, T. Gridley. (2019). Abundance estimates of an isolated population of common bottlenose dolphins in Walvis Bay, Namibia 2008-2012. African Journal of Marine Science 41(1). Take home message: At under 100 individuals, this is one of the smallest populations of any mammal in southern Africa but is exposed to an increasing number of human threats including marine tourism, harbour expansion and habitat degradation. Paper available on our website: http://seasearch.co.za/research/ or Researchgate profiles. ABSTRACT The coastal population of common bottlenose dolphins (*T. truncatus*) found in Namibia is regionally isolated and unique. This population faces several potential anthropogenic threats, especially in Walvis Bay, including boat-based tourism, a commercial harbour undergoing expansion and aquaculture for oysters and mussels. Between 2008 and 2012, 238 boat-based surveys were conducted, resulting in 170 encounters with bottlenose dolphins. Group size varied from 1 to 45 individuals (mean = 10.7). Encounter rates, group size and total number of animals identified were higher in winter than summer seasons. The number, and survival and immigration parameters of dolphins using Walvis Bay was investigated using Robust Design and Huggins closed population mark-recapture models. The highest numbers estimated were in the first and last years of the study, with estimates of 74 to 82 and 76 to 77 (number identified and upper 95% confidence interval respectively). The only previously available data from an incomplete study in the early 1990s suggested that the population was between 100 and 150 individuals at that time. Although no linear trend in population size was obvious during this study, the clear evidence of isolation, small population size, low annual birth rate, and potential long-term decrease in numbers since the early 1990s is concerning. Further work to collect data on demographic parameters is urgently recommended with a view to obtaining increased protection. -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Simon Elwen Ph.D. NRF Research Fellow at the Mammal Research Institute, University of Pretoria Based at Sea Search Africa - 4 Bath Rd, Muizenberg, Cape Town. Phone: +27 21 788 1206 (Office SA), +27 71 139 5951 (Mob SA) www.seasearch.co.za & www.namibiandolphinproject.org <http://www.namibiandolphinproject.org>
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